Regional heat flow variations across the sedimented Juan de Fuca Ridge eastern flank: Constraints on lithospheric cooling and lateral hydrothermal heat transport

Davis, Earl E.; Chapman, David S.; Wang, Kelin; Villinger, Heinrich; Fisher, A. T.; Robinson, Scott; Grigel, J.; Pribnow, D.; Stein, Joshua S.; Becker, Keir

doi:10.1029/1999jb900124

Cited by 136 publications

(203 citation statements)

References 33 publications

(26 reference statements)

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“…The mean observed value for this age lithosphere is 80-90 mW/m 2 [20,21], and the difference from conductive models is commonly attributed to the effects of hydrothermal circulation. Heat flow studies at the Juan de Fuca Ridge have shown that, where the oceanic crust is covered with a few hundred metres of sediment, heat flow values return to values consistent with plate cooling models within about 20 km of basement outcrops, suggesting that a relatively thin sediment cover can isolate the hydrothermal system from the open ocean [22]. However, our observed values are low despite the relatively thick sediment cover.…”

Section: Discussioncontrasting

confidence: 53%

Low heat flow from young oceanic lithosphere at the Middle America Trench off Mexico

Minshull

Bartolomé

Byrne

et al. 2005

Earth and Planetary Science Letters

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Seismic reflection profiles across the Middle America Trench at 208N show a high amplitude bottom simulating reflector interpreted as marking a phase transition between methane hydrate and free gas in the pore space of both accreted and trench sediments. We determine the depth of the hydrate-gas phase boundary in order to estimate the geothermal gradient and hence the heat flow beneath the trench and the frontal part of the accretionary wedge which overlies the downgoing plate. After correction for sedimentation, heat flow values in the trench and through the accretionary wedge are only about half of the values predicted by plate cooling models for the 10 Ma subducting lithosphere. There is no systematic correlation between heat flow in the accretionary wedge and distance from the trench. A comparison with heat flow predicted by a simple analytical model suggests that there is little shear heating from within or beneath the wedge, despite the high basal friction suggested by the large taper angle of the wedge. The geothermal gradient varies systematically along the margin and is negatively correlated with the frontal slope of the wedge. Some local peaks may be attributed to channelised fluid expulsion. D

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Section: Discussioncontrasting

confidence: 53%

Low heat flow from young oceanic lithosphere at the Middle America Trench off Mexico

Minshull

Bartolomé

Byrne

et al. 2005

Earth and Planetary Science Letters

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“…F1A), then flowing toward the east. Some results from Leg 168 were consistent with this view, including seafloor heat flow and basement temperatures that increased and basement fluids that were warmer and more altered with greater distance to the east along the drilling transect (e.g., Davis et al, 1992Davis et al, , 1999Elderfield et al, 1999). But there were inconsistencies with this conceptual model of largescale hydrogeologic flow, especially after Leg 168 results were considered.…”

Section: Operations During Ocean Drilling Program (Odp)supporting

confidence: 63%

“…In addition, reexamination of existing bathymetric data and collection of additional data along western end the Leg 168 transect showed basement outcrops to the north and south that could allow hydrothermal fluids to recharge and discharge, with flow occurring nearly perpendicular to the transect (Hutnak et al, 2006). There was also the vexing problem of explaining where fluids flowing toward the east at the western end of the Leg 168 transect might exit the crust (e.g., Davis et al, 1999). It is not possible for large volumes of fluid to recharge the crust, flow laterally across tens of kilometers, and then be stored indefinitely.…”

Section: Operations During Ocean Drilling Program (Odp)mentioning

confidence: 99%

Expedition 301 synthesis: hydrogeologic studies

Fisher¹

2009

Proceedings of the IODP

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Integrated Ocean Drilling Program Expedition 301 was part of a long term series of operations and experiments focused on quantifying hydrogeologic, lithologic, biogeochemical, and microbiological properties, processes, and linkages in basaltic crust on the eastern flank of the Juan de Fuca Ridge. This paper summarizes peer-reviewed hydrogeologic studies published since the end of Expedition 301. Regional survey data show that patterns of fluid circulation in basement on this ridge flank are complex, including components of fluid flow in the ridge-parallel (along-strike) direction. Numerical models show that hydrothermal circulation can form a hydrothermal siphon between recharging and discharging basement outcrops that penetrate regionally thick sediments, provided basement permeability is ≥10 -12 m 2 . Simulated fluid temperatures in upper basement between outcrops are consistent with observations (60°-65°C) if large-scale basement permeability is ~10 -11 m 2 . Other models show that basement conditions in the Expedition 301 field area may be undergoing thermal rebound following the end of an earlier phase of open hydrothermal circulation that extracted a larger fraction of lithospheric heat than is extracted today. This hypothesis is consistent with trends in basement geophysical properties, as determined with Expedition 301 wireline logs and tests on core samples from upper basement, which suggest that upper basement has not been warmer than it is at present. Drill string packer experiments in upper basement during Expedition 301 indicate a layered crustal structure, with bulk permeabilities from 10 -12 to 10 -11 m 2 . Additional hydrogeologic analyses were completed using the formation pressure response to the long-term flow of cold bottom seawater into basement at Site U1301 during 13 months after drilling, as observed at Site 1027 (2.4 km away). These analyses suggest large-scale permeability at the low end of values indicated by packer testing, 0.7 × 10 -12 m 2 to 2 × 10 -12 m 2 . Results from these two sets of measurements, and the difference between these permeability estimates and others based on modeling and analyses of formation responses to tidal and tectonic perturbations, may be reconciled if the upper crust in this area is anisotropic with respect to basement permeability. This hypothesis will be tested during and after the next drilling expedition in this area, when multidirectional crosshole experiments are run using a network of sealed borehole observatories.

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“…If generalized to the entire flow path between Blanco Saddle and 47°N, heating at this rate corresponds to an 18 month transit time. However, Davis et al [1999] measured heat flux values in the western half of the basin near 48°N that do approach the conductive plate model. Roughly consistent with this tripling of observed heat flow moving north, potential temperature anomalies increase sharply beyond 47°N, acquiring an additional 0.01°C in only 1 degree of latitude (Figure 3c).…”

Section: Discussionmentioning

confidence: 99%

Geothermal heating and the properties of bottom water in Cascadia Basin

Hautala

Johnson

Bjorklund

2005

Geophysical Research Letters

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[1] A new compilation of CTD data sheds light on the circulation and properties of bottom water within Cascadia Basin. A relatively high salinity water mass is revealed in a region of likely bottom water inflow east of the Blanco Fracture Zone. Water mass distributions and the deep geostrophic shear field are consistent with a general cyclonic circulation within the basin and suggest a northward-flowing boundary current next to the deep continental slope. Shifts in temperature-salinity relationships are consistent with a vertical transition from waters of northern origin to waters of southern origin approaching the seafloor. This vertical water-mass transition complicates the interpretation of temperature anomalies. We redefine the temperature anomaly due to geothermal activity and the thickness of the layer influenced by seafloor heating. Simple heat budget calculations lead to a residence time of about one year for the bottom water, shorter than suggested by previous studies. Citation: Hautala, S. L., H. P. Johnson, and T. Bjorklund (2005), Geothermal heating and the properties of bottom water in Cascadia Basin, Geophys. Res. Lett., 32, L06608,

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Regional heat flow variations across the sedimented Juan de Fuca Ridge eastern flank: Constraints on lithospheric cooling and lateral hydrothermal heat transport

Cited by 136 publications

References 33 publications

Low heat flow from young oceanic lithosphere at the Middle America Trench off Mexico

Low heat flow from young oceanic lithosphere at the Middle America Trench off Mexico

Expedition 301 synthesis: hydrogeologic studies

Geothermal heating and the properties of bottom water in Cascadia Basin

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